This is a question for Scott/LazyBkpr ~ watch for his input 
I'm just one guy.. I'll give my thoughts, but the group mind is much better..
From the description it sounds like a cast, probably with a virgin queen. If they DO move into your box, it will be hard for them to build up with so few bees.
What do you want to do if they take up residence?
Do you want another hive? Is it worth the struggle to save them?
If you do.. Adding a frame of brood with bees will give them a better chance.
If you have a queen you want to replace.. remove her, let them go queenless for 10 - 12 hours and combine this small cast with the newspaper method.. another three or four hours as they begin to remove the paper and slowly combine...
Make sure there is a queen in this cast and its not what you thought originally, stragglers.. I'm sure others will have input and different ideas strategy.